1. Field of the Invention
The present invention relates to a rotor of a rotary electric machine.
2. Discussion of the Background
A known rotor of a rotary electric machine includes a rotor core, which is constituted of multi-layered annular steel plates and has slots, each in which a permanent magnet is disposed (for example, refer to Japanese Patent No. 4244111).
As illustrated in FIG. 4, a rotor 105 of a rotary electric machine according to Japanese Patent No. 4244111 includes a rotor core 151, which is constituted of limited electromagnetic steel plates disposed inside an armature 101; through-holes 158 and 159 formed in both wing parts; rectangular slots 152 and 153, which are interposed between the through-holes 158 and 159 and separated by a center part of the rotor core 151; permanent magnets 106A and 106B fit into the slots 152 and 153, respectively; a protruding pole part 154 disposed on the upper surfaces of the permanent magnets 106A and 106B; and a bridge (center rib) 155 connecting the protruding pole part 154 and the rotor core 151 between the slots 152 and 153. Stepped parts 152E and 153E, which protrude toward the bridge 155, are disposed on inner circumferential corners 152B and 153B on the bridge 155 sides of the slots 152 and 153, and stepped parts 152F and 153F, which protrude in a direction opposite to the bridge 155, are disposed on outer circumferential corners 152C and 153C on the opposite side of the bridge.
With the rotor 105 having the above-described configuration, by disposing the stepped parts 152E and 152F, 153E, and 153F in the slots 152 and 153, stress concentration due to a centrifugal force can be dispersed at the corners 152B, 152C, 153B, and 153C of the slots 152 and 153 while rotating at high speed.